1. Field of the Invention
This invention relates to inspection platens, more particularly to inspection platens that do not require an alteration of the material to be inspected.
2. Background of the Invention
Inspection for defects is critical in any process of manufacture. Whether the inspection is used as an end process or used in setting up the manufacturing flow, it is important that the inspection system be exact and thorough. Recently, companies have begun to move to automated inspection systems to eliminate both the overhead of a huge inspection effort and to provide more consistent results.
Inspection systems typically have some kind of viewing apparatus with a platform or platen to which is mounted the object of interest. The object is often held through vias in the object or device with a vacuum from under the platen or in some type of carrier. These have many problems, two of which are the vias themselves, and the uniformity of the objects surface.
The vias are normally cut into the carrier, platform or platen some small distance from the edge. This has obvious problems when inspecting thin films, where the vias may propagate into cracks if in the object, or cause other defects of visible anomalies if milled into a platen. Additionally, if the object of interest is a thicker item, such as an integrated circuit, the carrier may not hold the IC down enough to flatten any "potato chipped" areas of the chip uniformly, which can lead to problems in the inspection accuracy.
Another problem the current systems possess is in the inspection of translucent or transparent materials, from white ceramic to fiber optic cables. In these cases the platen must be glass or some similarly transparent material, and the vias would cause problems in the final product, since the light would be transmitted differently through the holes or vias than through other parts of the system. Therefore, some type of non-invasive means of holding objects to a platen that does not invade the material and allows the passage of light is needed.